This is an example of a multi-factor analysis. It is
our intention to demonstrate how the data can be interrogated
to answer specific questions below the 6th field watershed
level. This example will select sites at the stream reach
level. We are asking the GIS, in this example, to locate
unconfined,
low gradient
streams (streams with gradients 0.0 to 3.5% or 0.0
to 2.0 degrees), that pass over
hydric
soils.
This analysis was accomplished by doing a series of selections
in ARCView and then using the Geoprocessing Wizard to
clip the stream layer so that only the stream segments
meeting all of these criteria were selected.
Step 1: Using the derived stream gradient layer,
we used the query tool to select stream segments that
had a stream gradient ranging from 0-2 degrees.
Step 2: We then intersected the low gradient streams
with the confiment layer to select low gradient, unconfined
stream segments.
Step 3: We intersected the low gradient, unconfined
stream segments with the soils layer and selected low
gradient, unconfined segments flowing through hydric soils.
This analysis located areas, approximately
7.5% of the streams, that may be potentially useful sites
for instream or off-channel restoration actions.
Please address questions or comments
to:
Dr. Ralph Garono
Principal Investigator
Earth Design Consultants, Inc.
rgarono@earthdesign.com
Laura Brophy
Principal Investigator
Green Point Consulting
brophyl@peak.org |
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